Large amounts of bulk materials such as coal, ore, scrap metal and wood are transported in open railroad cars. The design of the cars varies widely depending upon the shape and the weight of the bulk cargo. Some of the cars include hoppers on the bottom of the car for unloading the cargo. These unloading means require the cargo to be free flowing. Some materials which are free flowing and normally capable of being unloaded through hoppers may be difficult to unload if frozen or wet. In addition, the cargo may settle during transit to become at least partially coherent. Since most bulk cargo carrying cars are open, the addition of water or ice to the cargo may prevent its efficient unloading characteristics of the cargo, the hoppers themselves are subject to malfunction and cause added expense in manufacture of the car and its maintenance. The unloading of such cars from the open top alleviates many of the problems associated with bulk cargo cars employing bottom unloading hoppers.
There are also bulk cargo carrying cars that have no provision for unloading through the bottom of the cars. The cargo can be unloaded from these cars in a variety of ways. Material conveyors can be placed within the cars or if the cargo is magnetic, it can be removed with electromagnets. Another means of unloading bulk cargoes from cars having open tops is to at least partially invert the car and pour the cargo from the car into some receiving means.
Prior art devices for such purposes either discharge the cargo into a pit below the apparatus or the apparatus itself is raised above ground level as, for example, on a trestle. The space beneath the apparatus receives the cargo dumped from the car and any material handling equipment used to transport the unloaded cargo operates within that space.
The dumping of bulk cargo in such a manner creates several major problems. One problem is the expense of elevating the track and providing powered means to place the cars within the unloading device. Another is the expense of excavating and maintaining a pit beneath the unloading device.
Still another problem with conventional dumping techniques that use elevated track or a pit results from the free fall distance of the cargo. When the cargo free falls a distance that corresponds to at least the height of the car, large amounts of dust can be generated. Furthermore, if the bulk cargo is stacked, as, for example, pulpwood logs, the fall may entangle the logs and create further material handling problems.
The present invention provides a means of unloading bulk cargoes that does not rely on the cargo's being free flowing since the cargo is removed through the open top of the car. The cargo does not fall a large distance and, therefore, the creation of dust is minimized. Furthermore, if the cargo is ordered, for example, stacked pulpwood logs, the unloading will not disorder the load in an amount that would significantly affect further cargo handling. In addition, the cargo once removed from the railroad car is completely enclosed and the unloading of the receiver box into which the cargo is initially placed can be readily controlled and interrupted.
The invention is adapted for use with a large variety of railroad cars and can be used to unload a variety of bulk materials.
Additional advantages of the invention will be set forth, in part, in the description which follows, and in part, will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.